فاضل عبد العباس حسن الشتالي

In this research, a study was conducted experimentally to investigate the scour hole dimensions downstream the combined structures which consist of weir and gate due to the effect of the coefficient of discharge (Cd) due to flow above the compound weir to the flow under the gate. Fifteen models have been designed, and every model is formed from composite weir consisting of two geometric shapes with rectangular gate of constant dimensions. In this study, the experiment was conducted in a laboratory channel was constructed from blocks and concrete with length of 18 m, 1 m width and depth of 1 m, where the laboratory models were installed after 7 m from the main gate which controlled the passage of water from the main reservoir into the flume. At the beginning, the calibration process was conducted to identify the actual discharge values that pass in the flume, and then seventy-five experiments were conducted in order to derive the formulae for investigating the non-dimensional depth (SD/d50) and non-dimensional length (SL/d50) of the scour hole due to the effect of (Cd). The bed of the flume was spread with sand layer of 30 cm thick for a distance of 4 m downstream combined structure. Two samples of sand were used in the experiments with different median size of particles (d50), the first of 0.7 mm and the second of 1 mm. Using the Excel program 2017, Six polynomial relationships were derived to calculate the dimensionless scour depth (SD/d50) in terms of the coefficient of discharge (Cd), where the resultant coefficients of determinations (R2) from these relationships were high.

In this research, a study was conducted experimentally to investigate the scour hole dimensions downstream the combined structures which consist of weir and gate. Twelve models have been designed and every model is formed from composite weir consists of two geometric shapes and three types of gates which are rectangular, semi-circular and triangular in shape, where multi factors were studied to find out the effect of changing geometry for both weir and gate, discharge flowing in the flume and particle size of bed material on the dimensions of scour hole. The experiments was conducted in a laboratory channel was constructed from blocks and concrete with length of 18 m, 1 m width and 1 m depth. The laboratory models were installed after 7 m from the main gate which is controlling the passage of water from the main reservoir into the flume. At the beginning, the calibration process was conducted to identify the actual discharge values that pass in the flume, then experiments were conducted to calculate the discharge coefficient for each model, which represents one of the studied factors within the dimensional analysis of the variables to derive the empirical formulas to calculate the dimensions of scour hole. Then the experiments were conducted in order to derive formulas to investigate the depth and length of the scour hole which formed in the sand floor spreading as a layer of 30 cm in thickness for a distance 4 m downstream combined structure. Two samples of sand were used in the experiments with different median size of particles ( d50), the first of 0.7 mm and the second of 1 mm. Using the dimensional analysis by π theorem and IBM SPSS 21 program, Four nonlinear relationships were derived to calculate the dimensionless scour depth (SD / d50) and another four nonlinear relationships calculates the dimensionless length of scour (SL / d50) depending on the laboratory results for each of the relative discharge (Qr), Froude number in terms of mean size of particle of bed material (Frd), non-dimensional difference head between upstream and downstream of combined structure (HD / d50), dimensionless distance between the lower edge of the weir and the upper edge of the gate (y3 / d50), dimensionless head over the crest of compound weir (h/d50) and the discharge coefficient (Cd), where the resulted determination coefficients (R2) from these relationships were good.

A series of laboratory experiments have been conducted to investigate the value of discharge coefficient (Cd) due to flow over compound sharp crested weir consists of a rectangular weir over a trapezoidal weir and below three shapes of gates with fixed dimensions which are rectangular, semi-circular and triangular. The effect for each of depth of water at the first step of compound weir (h1), depth of water at the second step of compound weir (h2), distance between lower edge of weir and top edge of gate (y3), total head upstream of combined structure (H), width of first step of compound weir (b1), width of second step of compound weir (b2) and width of third step of compound weir (b3) was taken into consideration in developing new formulas describing the relation between the coefficient of discharge (Cd) and other hydraulic and geometric parameters which are mentioned above. The experiments were conducted in a laboratory channel which is built of blocks and concrete. The total length of the flume is (18 m), width of (1 m) and (1 m) deep. The laboratory models were installed 7 m away from the main gate which controls running of the water from the main reservoir into the flume. Using the programs of Excel 2013 and IBM SPSS 21, three non-linear relationships were derived to calculate Cd in terms of the hydraulic and geometric parameters, where higher values for coefficients of determination (R2) has been achieved.

In this research, a study was conducted experimentally to investigate the scour hole dimensions downstream the combined structures which consist from weir and gate due to the effect of the relative discharge (Qr) between the flow above the compound weir to the flow under the gate. Twenty models have been designed, and every model is formed from composite weir consists of two geometric shapes with rectangular gate of constant dimensions. In this study, the experiments was conducted in a laboratory channel was constructed from blocks and concrete with length of 18 m, 1 m width and depth of 1 m, where the laboratory models were installed after 7 m from the main gate which is controlling the passage of water from the main reservoir into the flume. At the beginning, the calibra-tion process was conducted to identify the actual discharge values that pass in the flume, then one hundred exper-iments were conducted in order to derive formulas for investigating the non-dimensional depth (SD/d50) and non-dimensional length (SL/d50) of the scour hole due to the effect of (Qr). The bed of the flume was spreaded with sand as a layer of 30 cm in thickness for a distance 4 m downstream combined structure. Two samples of sand were used in the experiments with different median size of particles (d50), the first of 0.7 mm and the second of 1 mm. Using the Excel program 2013, Eight polynomial relationships were derived to calculate the dimensionless scour depth (SD/d50) in terms of the relative discharge (Qr), where the resulted coefficients of determinations (R2) from these relationships were high.

Many problems are generated by the presence of water from different sources in a pavement structure. The infiltration characteristics of the sub-base are an important component of the hydrological conditions. They are one of the components of the water balance and are necessary to describe the runoff response by a runoff model, in addition to describe the effect of water movement on changing the soil properties within infiltration. The present work emphasis on the characteristics of the infiltration by using laboratory model. This model is performed on remoulded sub-base samples of specific density and different heights, 10, 15, and 20cm, for different heads of water, 10, 15, and 20cm. The results revealed that there are significant effect of the water head and height of sub-base layer with high interaction of the wetting conditions of the sample. A statistical analysis was made to develop a relationship among the different studied parameters.

This study investigated the effect of reducing seepage under a hydraulic structure. This article aims to find positional equations for the control devices that reduce the seepage under the hydraulic structure. Using lengths and angles of sheet-piles under the hydraulic structure where the sheet-pile was placed up- and downstream, respectively, upon the hydraulic structure with anisotropy soil hypothetically affects both uplift pressure and seepage values. The experiments were conducted in two cases: in the first case, a couple of sheet-piles were oriented to the upstream passage; while in the second case, they were oriented to the downstream. Then, the second case was compared with three sheet-piles placed upstream, downstream, and intermediate to the passage. For each experiment (at the hydraulic toe position), the major affecting parameters such as the uplift pressure, gradient exit, and outlet flow rate were found. A correlation equation to correlate the exit gradient and discharge parameters was developed.

Rivers are considered one of the greatest reasons for the existence of human being gathering. They convey and collect downfall as natural flows, and hence rivers are supposed to be the main source of water that must be mastered, restrained, and controlled to meet the requirements of human beings. In general, humans shape their existence alongside the rivers, where these situations have many advantages and disadvantages. One of the disadvantages is the destruction by river floodings and erosion of their banks, so rivers should be controlled in order to minimize their severity. Also, one should know any critical points of rivers and use biological or mechanical ways to reduce erosion, such as river training structures (Espandar & Imam, 1994; Rashad & Kassaf, 2020). The most common and beneficial transversal river training structures are spur-dikes (Al-Yassiry, 2015), i.e. artificial networks situated on river banks at various angles with one edge on the bank and the other edge outstanding into the current. Spur-dikes are constructed and created for many purposes, such as: directing the flow for the chosen reach, increasing the flow depth for navigation, preventing erosion of rivers banks, establishing river alignment and cross-section, enhancing habitats of riverine aquatic, altering the surrounding view and aiding the accessibility to the river (Jafari & Masjedi, 2015; Rashad, 2021). Spur-dikes are typically made from stone, gravel, rock, earth, sand, or piles. They can be either submerged or non-submerged. The non-submerged ones are made in the case of impermeable spur-dikes since their top is exposed to severe erosion if submerged. On the other hand, spur-dikes can be designed in different plan view shapes, such as I, L, T, hockey, inverted hockey, and curved shapes (Fig. 1).